Spring Boot如何实现将图片或文件下载到浏览器的高效长尾词疑问？

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以Java Web方式展示图片到浏览器，以及下载服务器文件到浏览器的示例：

示例请求：- 展示图片到浏览器：`http://localhost:8080/image/1564550185144.jpeg`- 下载文件到浏览器：`http://localhost:8080/download/1564550185144.jpeg`

示例代码：

java// Servlet用于处理图片展示请求@WebServlet(/image/*)public class ImageServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String fileName=request.getPathInfo().substring(1); File file=new File(getServletContext().getRealPath(/) + images/ + fileName); if (file.exists()) { response.setContentType(image/jpeg); response.setHeader(Content-Disposition, inline; filename=\ + fileName + \); Files.copy(file.toPath(), response.getOutputStream()); } else { response.sendError(HttpServletResponse.SC_NOT_FOUND, File not found); } }}

// Servlet用于处理文件下载请求@WebServlet(/download/*)public class DownloadServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String fileName=request.getPathInfo().substring(1); File file=new File(getServletContext().getRealPath(/) + files/ + fileName); if (file.exists()) { response.setContentType(application/octet-stream); response.setHeader(Content-Disposition, attachment; filename=\ + fileName + \); Files.copy(file.toPath(), response.getOutputStream()); } else { response.sendError(HttpServletResponse.SC_NOT_FOUND, File not found); } }}

以Java web的方式显示图片到浏览器以Java web的方式下载服务器文件到浏览器

以Spring Boot的方式显示图片或下载文件到浏览器
请求例子：localhost:8080/image/1564550185144.jpeg

示例代码：

import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; import java.io.File; import java.io.IOException; @Configuration public class ImageShow implements WebMvcConfigurer { @Override public void addResourceHandlers(ResourceHandlerRegistry registry) { File directory = new File("image"); String path = null; try { path = directory.getCanonicalPath(); }catch (IOException e){ e.printStackTrace(); } registry.addResourceHandler("/image/**").addResourceLocations("file:"+path+"/"); } }

运行结果：

显示图片

下载文件

补充：springboot 下载图片并输出浏览器

@GetMapping(value = "v1/returnGroupCode",produces = MediaType.IMAGE_JPEG_VALUE) public byte[] returnGroupCode(@RequestParam("seriesUniqueCode") String seriesUniqueCode){ URL url = null; InputStream is = null; ByteArrayOutputStream outStream = null; HttpURLConnection httpUrl = null; try{ url = new URL(pdGroupcodeSeriesInfo.getQrCodeUrl()); httpUrl = (HttpURLConnection) url.openConnection(); httpUrl.connect(); httpUrl.getInputStream(); is = httpUrl.getInputStream(); outStream = new ByteArrayOutputStream(); //创建一个Buffer字符串 byte[] buffer = new byte[1024]; //每次读取的字符串长度，如果为-1，代表全部读取完毕 int len = 0; //使用一个输入流从buffer里把数据读取出来 while( (len=is.read(buffer)) != -1 ){ //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度 outStream.write(buffer, 0, len); } byte[] temp = outStream.toByteArray(); return temp; }

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